A sash window replacement in London can cost between £1,200 and over £4,000 per window. That is a wide range, and most homeowners have no idea what puts them at one end or the other until the quote arrives, by which point the budget has already been set.

What is more difficult is that London pricing differs from the rest of the UK. An increase in labour charges, conservation area regulations, restrictions on access, and the sheer variety of period property types throughout all increase costs in ways that a national average figure cannot measure.

This guide gives you verified 2026 prices for new sash windows and repairs, a clear explanation of all the cost variables, and the tools to read any quote with ease.

How much do new sash windows cost in London?

The cost of sash windows in London largely depends on the materials used. The following are the 2026 price ranges of professionally supplied and fitted sash windows.

Window type Supply only Supply & fitted (per window)
uPVC sash window From £800 £1,200 to £2,800
Timber sash window From £1,500 £2,000 to £4,000
Bespoke timber sash From £2,000 £2,500 to £4,000 +

uPVC sash windows

uPVC sash window prices in London begin at £800 supply, and prices increase to £1,200-£2,800 fitted. It is low-maintenance; however, it is not permitted in most conservation zones or listed buildings.

Timber sash windows

Timber sash windows in London are between £2,000 and £4,000. High-end products like Accoya come with a 50-year anti-rot warranty and are priced accordingly.

Sash window repair cost in London

Not every window problem needs a full replacement. Sash window repair in London can be a more economical solution, especially for older buildings and conservation areas. The following are the verified repair cost ranges.

Repair type Cost per window (London)
Sash cord replacement £100 to £200
Draught-proofing £250 to £450
Repainting (internal and external) £180 to £500
Rot repair and timber restoration £200 to £800+
Full refurbishment and overhaul £600 to £1,200+
Slimline double glazing retrofit £700 to £1,500+

What affects sash window prices in London?

Several factors influence the sash window prices in London. Understanding these will help you evaluate any quote.

  • Material : Timber is expensive compared to uPVC. Premium products such as Accoya cost more but offer a longer lifespan.
  • Windows size : Bigger windows require more materials, heavier glazing, and larger mechanisms, which increase the price.
  • Type of glazing : Single glazing is the cheapest, whereas slimline double glazing enhances thermal and sound performance.
  • Access : Scaffolding may be needed when using the upper-floor window, adding £250- £500 per week.
  • Conservation area or listed building : Specialist materials and planning compliance add cost.
  • Number of windows : When the project is large, this leads to a low-per-window cost due to economies of scale.

Repair or replace? How to decide

When to repair

  • The frame is structurally stable and slightly damaged, with broken cords or draughts.
  • The house is located in a conservation area and cannot be fully replaced without planning permission.
  • Repair is much cheaper than replacement, and the windows still have life left in them.

When to replace

  • When frames have massive decay, structural defects or damage beyond repair
  • Repair costs are cumulative and exceed or are nearly equal to the cost of the new window.
  • Full replacement is a better, future-proof option because it is more practical for a wider renovation.

Conclusion

The cost of sash windows in London is calculated based on several factors. Every pound in the quote includes the actual material selected, the access you need, the glazing you ordered, and the location of your property. When you know these factors, you will be able to interpret those numbers with confidence.

Whether it is a one-window or a full-period house, the right decision is always made with complete information and a simple analysis by someone who understands the planning regulations of London. In such cases, contact SJB Sash Windows and arrange a completely free site survey and have an all-inclusive, no-obligation quote for your property.